1. Field of the Invention
This invention relates to the manufacture of fragmentation warheads. More particularly, this invention relates to methods for treating the materials from which fragmentation warheads are made in order to control the size and/or shape of the fragments which will be produced by the warheads.
2. Description of the Prior Art
Fragmentation warheads are well known. They are used in military operations both as armor piercing devices and as anti-personnel devices.
In armor piercing applications anything from a thin wooden wall to a reinforced concrete or steel structure may be the target. In this case, it is desirable to have the nose (portion that actually strikes the target) of the warhead be very hard and strong and the body (casing) which follows the nose be formed of material which breaks up into relatively large and preferably incendiary type fragments. Relatively large fragments are desirable in armor piercing applications in order that the fragments have some armor piercing capability themselves.
On the other hand, in anti-personnel applications it is desirable to have the warhead casing break up into a very large number of small, high velocity fragments when the warhead is detonated. The reason for this is self evident if the warhead is thought of as being detonated in the air over a widely dispersed plurality of targets.
Several methods of manufacture have been devised in attempts to control the size and shape of fragments produced by warheads upon detonation. Certain of these methods involve the use of scoring to produce zones of weakness in the warhead casing. When a scored warhead is detonated, the casing is supposed to break in the scored areas. However, due to the violent force of the explosion, such warhead casings often break up into much smaller fragments than planned upon detonation. Furthermore, scoring produces a rough outer surface which impedes the smooth travel of the warhead through air prior to detonation and, for this reason, is undesirable. Still further, scoring is an expensive process.
Other methods used in attempting to control the size and shape of warhead fragments utilize differential heat treatment to provide alternating bands or areas of strength and weakness in the material of the warhead casing. In order to be successful, these methods require the use of very sophisticated apparatus to isolate the areas which are to be heated (tempered) from the areas which are not. Thus, these methods are expensive and, because of the sophisticated nature of the apparatus, sometimes unreliable.